In the erecting and demolishing of large structures, such as outdoor concrete bridges, it is necessary to erect a heavy-duty support system that can hold up the structure either as it is being assembled or erected, or as it is being taken apart. This support structure must therefore be capable of holding up very great masses, and must hold them stably. At the same time it must be relatively easy to assemble and dissassemble it so that excessive job time is not lost.
The standard system according to DIN 4411 comprises steel-tube posts, steel lattice elements, and steel stands or trestles that are interconnected together by clips or pins to a rugged assembly. Erecting such a support system is an extremely difficult and onerous job, as is taking it down. In addition the various parts of this system are a problem to keep track of when not assembled together. As a result construction, which term here includes the erection and demolition of a structure, with such an arrangement is very expensive, due mainly to the setup and takedown times.